In the process of multi-domain path computation, if there is no mutual trust among domains, internal path information of a domain needs to be hidden from other domains, i.e., path confidentiality is needed.
When a PCE (Path Computation Element) provides path computation, the path confidentiality is realized through a mechanism of a PATH-KEY (path key), which technology is specified in RFC5520. The general processing of the technology is described as follows.
A PCE computes a path in a domain, and before returning a path computation result to a PCE in another domain, a PATH-KEY sub-object may be adopted to replace a detailed intra-domain path. In front of the PATH-KEY sub-object, a TE Router ID (traffic engineering router identifier) of an ingress boundary node is reserved as one hop. In the standard, it is suggested that the PATH-KEY information be reserved in the PCE for ten minutes.
In the process of path establishment through signalling, when the ingress boundary node is reached, the ingress boundary node then requests to acquire an intra-domain path corresponding to the PATH-KEY from the corresponding PCE.
In addition, it is mentioned in RFC5521 that a PATH-KEY can be used to perform intra-domain separation.
The standard has a simple description of the use of PATH-KEY, but it does not mention the method for storing the PATH-KEY for a long term. However, it is important to store PATH-KEY information for a long term, for example, in the following situation.
After a long time, the PATH-KEY in the PCE already does not exist. However, it is necessary at the moment to initiate end-to-end path recovery or optimization among domains. If a new working path and an old protection path pass through the same domain, when computing the new working path in the domain, it is necessary to separate the new working path from the old protection path associated therewith. In this case, it is needed to query intra-domain path information corresponding to the old protection path via a PATH-KEY stored for a long term.